1. Field of the Invention
The present invention relates to a chip discharge conveyor system of the type wherein a used coolant containing therein chips of different sizes including cutting tips or grinding chips of iron-, aluminum- or copper-based metal that have been discharged from the machine tools during a metal working process such as cutting or grinding is charged into a used coolant treatment tank from the above, and the chips of different sizes contained in the used coolant are conveyed by a single conveyor system and subsequently discharged outside the used coolant treatment tank.
2. Description of the Related Art
When a metal working process, such as cutting or grinding, is effected on a metallic material with a machine tool, a coolant such as water containing a cutting oil or a lubricant dissolved therein is used for cooling a cutting tool, a grinding tool and/or a workpiece. Conventionally, as a chip discharge conveyor system for catching and removing chips from a used coolant discharged from the machine tool, a conveyor system comprised of a hinged belt is used.
One example of such conventional chip discharge conveyor systems is shown here in FIGS. 14 to 16. The conventional conveyor system 51 is equipped with an endless hinged belt 53 disposed inside a used coolant treatment tank 52, a driving sprocket 54 around which a side chain 53c mounted on the hinged belt 53 is wound, and a driven tail disk 55 for slide contact with the side chain 53c at a conveyor tail portion T. In these figures, reference character 52a denotes a horizontal bottom plate of the used coolant tank 52, 52b denotes a sloped bottom plate extending obliquely upward from the horizontal bottom plate 52a, 56 denotes outer cleats attached to an outer circumferential surface of the hinged belt 53, and C denotes an advancing direction of the hinged belt.
In the chip discharge conveyor system 51, a coolant containing therein chips of different size is charged into the used coolant treatment tank 52 from above (in the direction indicated by the arrow A in FIG. 14), chips of larger size (hereinafter referred to as xe2x80x9clarge chipsxe2x80x9d) are caught on discharge belt run 53a on an upper side of the hinged belt 53. The discharge belt run 53a travels continuously along a horizontal path and an upwardly sloped path extending parallel to the sloped bottom plate 52b. As the discharge belt run 53a travels along the sloped path, the large chips are held by the outer cleats 56. Then, at the top of the used coolant treatment tank 52, the large chips are discharged from a discharge opening 57 to the outside of the used coolant treatment tank 52 (in the direction indicated by the arrow B in FIG. 14). Chips of smaller size (hereinafter referred to as xe2x80x9csmall chipsxe2x80x9d) which have not been caught by the discharge belt run 53a sediment onto a return belt run 53b (of an inner circumferential surface of the belt 53) and the horizontal bottom plate 52a. 
In the conventional chain discharging conveyor system 51 previously described, large chips (such as curled chips, ball-like chips formed by curled chips entangled together, or long chips) contained in a used coolant together with small chips are caught on the discharge belt run 53a on an upper side of the hinged belt 53. However, the small chips fall by gravity down through a clearance between adjacent two hinged plates of the discharge belt run 53a, a clearance between each longitudinal edge of the hinged belt and the corresponding sidewall of the used coolant treatment tank 52 and a clearance in the side chain. A part of such small chips sediments onto the inner circumferential surface of the return belt run 53b on the lower side of the hinged belt 53. The remainder of the small chips, that have not been caught on the return belt run 53b, sediments onto the bottom plate of the used coolant treatment tank 52 (see chips noted by K2 FIG. 4).
The small chips deposited on the inner circumferential surface of the return belt run 53b are then conveyed toward the conveyor tail portion T. As the return belt run 53b makes an upward turn at the conveyor tail portion T, deposits of small chips on the return belt run 53b drop one after another and pile up or accumulate into a rod-like mass at the upturned position of the hinged belt 53. Such piling-up of the small chips also occurs even when two sprockets connected by a shaft are used in place of the tail disk 55. The mass of small chips piled up inside the upturned belt portion gradually forces the hinged belt 53 toward vertically upward and downward directions. This may result in an accidental stop of the conveyor system 51. When such stop occurs, the hinged belt 53 must be removed so that the inside of the used coolant treatment tank 52 can be cleaned. The foregoing problem is caused due to the absence of a mechanism or a structure for enabling positive discharge of small chips adhering by sedimentation to the return belt run.
It appears clear from the foregoing description that the conventional chip discharge conveyor system composed of a hinged belt is per se unable to treat a used coolant containing chips of different sizes. To deal with this problem, a separate drum filter is disposed adjacent to the conveyor system, as disclosed in U.S. Pat. No. 5,992,642, granted Nov. 30, 1999. This arrangement, however, requires a large occupied space. In another improved conventional arrangement, a scraper type conveyor (for discharging small chips) and a hinged belt type conveyor (for discharging large chips) are disposed side by side or one above another. This arrangement requires a large space for installation and two separate power sources, which deteriorate the power consumption and cost efficiency. An additional drawback associated with the two-story arrangement is a considerable deterioration in the maintainability of the lower conveyor.
It is accordingly a general object of the present invention to overcome the foregoing drawbacks of the prior art.
A more specific object of the present invention is to provide a chip discharge conveyor system using a hinged belt, which is capable of catching and discharging large chips by means of a discharge run of the circulating endless hinged belt, and at the same time, catching small chips on a return run of the hinged belt and subsequently discharging the small chips outside the conveyor system without involving formation of a large mass of small chips at an upwardly turned portion of the return belt run, thereby ensuring that a used coolant containing chips of different sizes can be treated only by using a single chip discharge conveyor system without requiring a large space for installation and involving an accidental stop of the conveyor system caused due to jamming of the chips.
To achieve the foregoing object, according to the present invention, there is provided a chip discharge conveyor system including an endless hinged belt disposed in a used coolant treatment tank in such a manner that the endless hinged belt travels to circulate while making a turn at a conveyor tail end and a chip discharge end, wherein a used coolant containing chips of different sizes is charged into the used coolant treatment tank from the above, the chips of different sizes contained in the used coolant are caught and then conveyed to the chip discharge end where the chips are discharged outside the used coolant treatment tank. The outer cleats are attached to an outer circumferential surface of the hinged belt. The chip discharge conveyor system further includes a partition plate disposed below a discharge run of the hinged belt in confronted relation to the discharged belt run along the length thereof, and a cylindrical member disposed inside the conveyor tail end where a return run of the hinged belt makes an upward turn. The cylindrical member extends in the width direction of the conveyor tail end so that small chips caught on the return belt run are transferred onto the partition plate via an outer circumferential surface of the cylindrical member and subsequently conveyed by means of an inner circumferential surface of the hinged belt and the partition plate.
In one preferred form of the present invention, inner cleats are attached to the inner circumferential surface of the hinged belt.
It is preferable that a discharge mechanism is provided to discharge the small chips from the partition plate in a lateral direction of the used coolant treatment tank.
The circulating endless hinged belt of the present invention has a discharge belt run formed on an upper side of the hinged belt, and a return belt run formed on a lower side of the hinged belt. The term xe2x80x9clongitudinal directionxe2x80x9d is used herein to refer to a direction parallel to the direction of travel of the circulating endless belt. The term xe2x80x9cwidth directionxe2x80x9d is used herein to refer to a direction perpendicular to the travel direction of the hinged belt. The term xe2x80x9clarge chipsxe2x80x9d is used herein to refer to long chips, curled chips, a mass of chips all having a size which can be blocked from passing through the hinged belt and thus trapped or caught by the discharge belt run. The term xe2x80x9csmall chipsxe2x80x9d is used herein to refer to those chips of a size that can sediment through the joint between adjacent two hinge plates, a clearance between each longitudinal edge of the hinged belt and the corresponding sidewall of the used coolant treatment tank, and a clearance formed in a side chain.
In the chip discharge conveyor system of the present invention, when a used coolant containing chips of different sizes is charged into the used coolant treatment tank, large chips are trapped or caught on the discharged belt run, then transported along the discharge belt run, and finally discharged outside the used coolant treatment tank. During that time, small chips, which have not been caught on the discharge belt run, partly settles by sedimentation on the partition plate. Another part of the small chips is caught on the return belt run (inner circumferential surface of the hinged belt), and the remainder of the small chips deposit by sedimentation onto the bottom of the used coolant treatment tank.
The small chips sedimented on the bottom of the treatment tank are scraped off by the outer cleats of the return belt run, then scooped up as the return belt run make an upward turn at the conveyor tail end, subsequently conveyed by the discharge belt run together with the large chips, and finally discharged from the discharge end to the outside of the used coolant treatment tank.
At the same time, small chips caught on the return belt run (the inner circumferential surface of the hinged belt) are conveyed by the return belt run until they arrive at the conveyor tail end. As the hinged belt makes an upward turn at the conveyor tail end, the small chips are transferred onto the partition plate via the cylindrical member located at a turning position of the hinged belt. Subsequently, the small chips are conveyed on and along the partition plate toward the discharge end together with chips sedimented on the partition plate, and at the discharge end, the small chips are discharged outside the used coolant treatment tank.
In this instance, if the inner cleats are not provided on the inner circumferential surface of the hinged belt, the small chips caught on the return belt run will be transferred along the circumferential surface of the cylindrical member onto the partition plate by means of hinge sleeves projecting outward from the respective joint portions between adjacent hinged plates of the hinged belt, and subsequently they are conveyed by the projecting hinged sleeves on and along the partition plate.
The inner cleats provided on the inner circumferential surface of the hinged belt operate to transfer the small chips from the return belt run onto the partition plate via the cylindrical member, and subsequently as the inner cleats advance with the discharge belt run, they convey the small chips along the partition plate toward the discharge end together with those chips sedimented on the partition plate. The thus provided inner cleats facilitate smooth transfer of the small chips from the return belt run to the partition plate at a turning position of the hinged belt and also achieve efficient conveyance of the transferred small chips and sediments of small chips on and along the partition plate.
Additionally, to make sure that the small chips which have been conveyed along the partition plate can be discharged outside the used coolant treatment tank, the discharge mechanism constructed to discharge the small chips from the partition plate in a lateral outward direction of the used coolant treatment tank is provided on the chip discharge end side. This facilitates efficient discharge of the small chips from a discharge end of the partition plate Lo the outside of the used coolant treatment tank.